I've got a stock Bottlehead Foreplay, ASL Wave-8s, and some speakers of my own design that recently came out of more than 2 years of storage.
After set up I discovered some problem with the system. There was no audible signal unless the volume was turned up to max. At max the sound was muted(obviously) and crackily. I isolated the amps and discovered that they are are working just fine so the problem is with the Foreplay.
The tubes were replaced just months before being put into storage so that wasn't the problem. After pulling out the amp and checking for bad joints and loose wires, I reconnected and everything worked beautifully, for a little while. After a few days of listening and enjoyment I changed an interconnect and the jostling of that action reverted the preamp to its previous state of disappointment and near silence.
My first instinct is still that it's a bad joint somewhere. There are a few connections that have a tarnished, dull, and sloppy look to them but even measuring resistance across them they seem to be OK. At one phase of my testing a little tap on the side of the enclosure caused a spike in the gain of the preamp which then slowly faded back to almost nothing.
I'm comfortable with the use of a multimeter, I'm not just not sure where to start looking short of following the instructions step by step. Does this sound like a bad capacitor or transformer? How does one discover if that is the case?
Where should I start and what am I looking for?
Thanks in advance.